Python reticulatus, also known as the (Asiatic) reticulated python,[4] is a species of python found in Southeast Asia. Adults can grow to 6.95 m (22.8 ft) in length[5] but normally grow to an average of 3–6 m (9.8–19.7 ft). They are the world's longest snakes and longest reptile, but are not the most heavily built. Like all pythons, they are nonvenomous constrictors and normally not considered dangerous to humans. Although large specimens are powerful enough to kill an adult human, attacks are only occasionally reported.

An excellent swimmer, Python reticulatus has been reported far out at sea and has colonized many small islands within its range. The specific name, reticulatus, is Latin meaning "net-like", or reticulated, and is a reference to the complex color pattern.[6]

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This species is the largest snake native to Asia. More than a thousand wild reticulated pythons in southern Sumatra estimated from 1.5 to 6.5 m (4.9 to 21.3 ft) in length and in weight from 1 to 75 kg (2.2 to 165.3 lb).[7] In general, reticulated pythons with lengths of more than 6 m (19.7 ft) are rare, though according to the Guinness Book of World Records it is the only extant snake to regularly exceed that length.[8] A reticulated python of the same length as a green anaconda may weigh only half as much as the bulkier anaconda.[8] One of the largest scientifically measured specimens, from Balikpapan, East Kalimantan, Indonesia, was measured under anesthesia at 6.95 m (22.8 ft) and weighed 59 kg (130 lb) after not having eaten for 3 months.[5] Currently Guinness World Records lists a snake named Medusa in Kansas City, Missouri, U.S., as the longest snake ever accurately measured in captivity, at 7.67 m (25.2 ft) and 158.8 kg (350 lb).[9] Widely published data of specimens that were reported to be several feet longer have not been confirmed.

Even the specimen once widely accepted as the largest-ever "accurately" measured snake, that being Colossus, a male kept at the Highland Park Zoo (now Pittsburgh Zoo & PPG Aquarium) in Pittsburgh, Pennsylvania, during the 1950s and early 1960s, with a peak reported length of 8.7 m (28.5 ft), recently turned out to be wrong. When Colossus died on April 14, 1963, its body was deposited in the Carnegie Museum of Natural History. At that time its skeleton was measured and found to be 20 ft 10 in (6.35 m) in total length, significantly shorter than the measurement previously published by Barton and Allen. Apparently, they had been adding a few extra feet to the measurements to compensate for "kinks", since it is virtually impossible to completely straighten an extremely large live python. Too large to be preserved with formaldehyde and then stored in alcohol, the specimen was instead prepared as a disarticulated skeleton. The hide was sent to a laboratory to be tanned, but it was either lost or destroyed.[10]

Numerous reports have been made of larger snakes, but since none of these were measured by a scientist nor any of the specimens deposited at a museum, they must be regarded as unproven and possibly erroneous. In spite of what was for many years a standing offer of $50,000 for a live, healthy snake over 9.1 m (29.9 ft) long by the New York Zoological Society (NYZS), known since 1993 as the Wildlife Conservation Society (WCS), no attempt to claim this reward was ever made.[11]

Skull diagram

The color pattern is a complex geometric pattern that incorporates different colors. The back typically has a series of irregular diamond shapes flanked by smaller markings with light centers. In this species' wide geographic range, much variation of size, color, and markings commonly occurs.

The "reticulated" net-like patterning that gives the reticulated python its name

In zoo exhibits the color pattern may seem garish, but in a shadowy jungle environment amid fallen leaves and debris it allows them to virtually disappear. Called disruptive coloration, it protects them from predators and helps them to catch their prey.[12]

Three subspecies have been proposed,[14] but are not recognized in the Integrated Taxonomic Information System (ITIS). The color and size can vary a great deal among the subspecies described. Geographical location is a good key to establishing the subspecies, as each one has a distinct geographical range.

The reticulated python lives in rain forests, woodlands, and nearby grasslands. It is also associated with rivers and is found in areas with nearby streams and lakes. An excellent swimmer, it has even been reported far out at sea and has consequently colonized many small islands within its range.[12] During the early years of the twentieth century it is said to have been common even in busy parts of Bangkok, sometimes eating domestic animals.[15]

Their natural diet includes mammals and occasionally birds. Small specimens up to 3–4 m (9.8–13.1 ft) long eat mainly rodents such as rats, whereas larger individuals switch to prey such as Viverridae (e.g. civets and binturongs), and even primates and pigs. Near human habitation, they are known to snatch stray chickens, cats, and dogs on occasion. Among the largest, fully documented prey items to have been taken are a half-starved sun bear of 23 kilograms that was eaten by a 6.95 m (22.8 ft) specimen and took some ten weeks to digest as well as pigs of more than 60 kg (132 lb).[16] As a rule of thumb, these snakes seem able to swallow prey up to one-quarter their own length and up to their own weight.[17] As with all pythons, they are primarily ambush hunters, usually waiting until prey wanders within strike range before seizing it in their coils and killing via constriction. However, there is at least one documented case of a foraging python entering a forest hut and taking a child.[18]

Attacks on humans are rare, but this species has been responsible for several human fatalities, in both the wild and captivity. They are among the few snakes that have been suggested to prey on humans. However, there are few authenticated cases of a snake species consuming human beings. Reports of human fatalities and unauthenticated sources of human consumption include:

Two incidents, apparently in early 20th century Indonesia: On Salibabu, a 14-year-old boy was killed and supposedly eaten by a specimen 5.17 m (17.0 ft) in length. Another incident involved an adult woman reputedly eaten by a "large reticulated python", but few details are known.[19]

Franz Werner reported a case from Burma occurring either in the early 1910s or in 1927.[11] A jeweller named Maung Chit Chine, who went hunting with his friends, was apparently eaten by a 6 m (19.7 ft) specimen after he sought shelter from a rainstorm in or under a tree. Supposedly, he was swallowed feet-first, contrary to normal snake behavior, but perhaps the easiest way for a snake to actually swallow a human.[20]

In 1932, Frank Buck wrote about a teenage boy who was eaten by a pet 25 ft (7.6 m). reticulated python in the Philippines. According to Buck, the python escaped, and when it was found, a human child's shape was recognized inside the snake. It turned out to be the son of the snake's owner.[11]

Among a small group of Aetanegritos in the Philippines, six deaths by python have been documented within a period of 40 years, plus one who died later of an infected bite.[18]

On September 4, 1995, Ee Heng Chuan, a 29-year-old rubber tapper from the southern Malaysian state of Johor, was killed by a large reticulated python. The victim had apparently been caught unaware and was squeezed to death. The snake had coiled around the lifeless body with the victim's head gripped in its jaws when it was stumbled upon by the victim's brother. The python, measuring 23 ft (7.0 m) long and weighing more than 300 lb, was killed soon after by the arriving police, who required four shots to bring it down.[11]

On October 23, 2008, a 25-year-old Virginia Beach, Virginia woman, Amanda Ruth Black, appeared to have been killed by a 13-foot (4.0 m) pet reticulated python. The apparent cause of death was asphyxiation. The snake was later found in the bedroom in an agitated state.[21]

On January 21, 2009, a 3-year-old Las Vegas boy was wrapped by an 18-foot (5.5 m) pet reticulated python, turning blue. The boy's mother, who had been babysitting the python on behalf of a friend, rescued the toddler by gashing the python with a knife. The snake was later euthanized because of its fatal wounds.[22]

Considering the known maximum prey size, it is technically possible for a full-grown specimen of Python reticulatus to open its jaws wide enough to swallow a human teenager, but the width of the shoulders of adult Homo sapiens would likely pose a problem for even a snake with sufficient size.

Oviparous, females lay between 15 and 80 eggs per clutch. At an optimum incubation temperature of 31–32 °C (88–90 °F), the eggs take an average of 88 days to hatch.[23] Hatchlings are at least 2 feet (61 cm) in length.[15]

Reticulated python with an unusual color pattern. Various color patterns are found in captive-bred specimens – some brought about by selective breeding.

Increased popularity in the pet trade is due largely to increased efforts in captive breeding and selectively bred mutations such as the "albino" and "tiger" strains. They can make good captives, but keepers should have previous experience with such large constrictors to ensure safety to both animal and keeper. Although their interactivity and beauty draws much attention, some feel they are unpredictable.[24][25] They do not attack humans by nature, but will bite and possibly constrict if they feel threatened, or mistake a hand for food. While not venomous, large pythons can inflict serious injuries, sometimes requiring stitches.

The huge size and attractive pattern of these snakes has made them favorite zoo exhibits, with several individuals claimed to be above 20 ft (6.1 m) in length and more than one claimed to be the largest in captivity.[26][27][28][29] However, due to their huge size, immense strength, aggressive disposition, and the mobility of the skin relative to the body, it is very difficult to get exact length measurements on a living reticulated python, and weights are rarely indicative, as captive pythons are often obese.[11] Claims made by zoos and animal parks are sometimes exaggerated, such as the claimed 15 m (49 ft) snake in Indonesia which was subsequently proven to be less than 23 feet (7.0 m) long.[30] For this reason, scientists do not accept the validity of length measurements unless performed on a dead or anesthetized snake which is later preserved in a museum collection or stored for scientific research.[11]

There are also dwarf forms of reticulated pythons, typically separate subspecies of the nominate mainland subspecies or crossbreeds thereof, from some islands that are north west of Australia, and where the adults rarely get more than 15 feet (4.6 m) long but are being bred to be much smaller. Males can be at most 5 feet (1.5 m) long, females a little longer.[citation needed]

P. r. jampeanusAuliya et al., 2002 – Kayaudi dwarf reticulated pythons or Jampea retics, about half the length,[23] or according to Auliya et al. (2002), not reaching much more than 2 m (6.6 ft) in length.[14] Found on Tanahjampea in the Selayar Archipelago south of Sulawesi. Closely related to P. r. reticulatus of the Lesser Sundas.[14]

P. r. saputraiAuliya et al., 2002 – Selayer reticulated pythons or Selayer retics. Found on Selayar Island in the Selayar Archipelago and also adjacent Sulawesi. This subspecies represents a sister lineage to all other populations of reticulated pythons tested.[14] According to Auliya et al. (2002) it does not exceed 4 m (13 ft) in length.[14]

The latter two are dwarf subspecies. Apparently, the population of the Sangihe Islands north of Sulawesi represents another such subspecies which is basal to the P. r. reticulatus plus P. r. jampeanusclade, but it is not yet formally described.[14]

The proposed subspecies "dalegibbonsi", "euanedwardsi", "haydnmacphiei", "neilsonnemani", "patrickcouperi", and "stuartbigmorei"[31][32] have not found general acceptance.

A recent phylogenetic study of pythons[33] suggested that the reticulated python as well as the Timor python are more closely related to Australasian pythons, suggesting that they are an intermediate form between the Australasian pythons and the Afro-Asian genus Python, and should therefore be placed in a separate genus. Reynolds et al. [3] described the genus Malayopython for this species and its sister species, the Timor python, M. timoriensis.